Transport comb for head stack assembly

ABSTRACT

An HSA transport comb includes an alignment pin extending from the comb body into a tooling hole of the actuator arm, and a separator finger in contact with a suspension assembly of an HGA with the transport comb in a second angular orientation with respect to the actuator arm, but not in a first angular orientation. The transport comb includes a restraining tower extending into a mass-reduction opening of the actuator arm. The restraining tower includes a first lobe that fits within the mass-reduction opening with the transport comb in the first angular orientation, but not with the transport comb in the second angular orientation. The restraining tower also includes a first neck that fits within the mass-reduction opening with the transport comb in either angular orientation, and has a neck height that is greater than the actuator arm thickness.

FIELD OF THE INVENTION

The present invention relates generally to the manufacture ofinformation storage devices, and in particular to a transport comb usedfor storing, shipping, and handling a head stack assembly (HSA) duringdisk drive manufacture.

BACKGROUND

The typical hard disk drive includes a head disk assembly (HDA) and aprinted circuit board assembly (PCBA) attached to a disk drive base ofthe HDA. At least one disk is rotably mounted to the disk drive base viaa spindle motor. The PCBA includes electronics and firmware forcontrolling the rotation of the spindle motor, controlling the angularposition of an actuator that positions a head stack assembly (HSA) towhich it belongs, and for providing a data transfer channel between thedisk drive and its host.

During operation of the disk drive, the actuator must rotate to positionhead gimbal assemblies (HGAs) of the HSA adjacent desired informationtracks on the disk. The actuator includes a pivot-bearing cartridge tofacilitate such rotational positioning. The pivot-bearing cartridge fitsinto a bore in the body of the actuator. One or more actuator armsextend from the actuator body. An actuator coil is supported by theactuator body, and is disposed opposite the actuator arms. The actuatorcoil is configured to interact with one or more fixed magnets in theHDA, typically a pair, to form a voice coil motor (VCM).

Each HGA includes a head for reading and writing data from and to thedisk. In magnetic recording applications, the head typically includes anair bearing slider and a magnetic transducer that comprises a writer anda read element. The magnetic transducer's writer may be of alongitudinal or perpendicular design, and the read element of themagnetic transducer may be inductive or magnetoresistive. In optical andmagneto-optical recording applications, the head may include a minor andan objective lens for focusing laser light on to an adjacent disksurface. The head is adhered to a suspension assembly that includes agimbal, load beam, bend region, and swage plate. The suspension acts topreload the head against the surface of the disk. The preload force isoften referred to as the “gram load.” It is desirable that the gram loaddoes not vary excessively among a population of HGAs, because the gramload affects the air bearing thickness and therefore also affects theperformance of the head.

However, the gimbal or bend region of one or more suspension assembliesin a population of HGAs may be inadvertently deflected beyond itselastic limit during the handling that is associated with disk drivemanufacture. Such handling damage can cause the gram load, and/or othersuspension assembly characteristics that affect the air bearing (e.g.,pitch static attitude, roll static attitude), to vary excessively withinthe population of HGAs, adversely affecting disk drive performance,manufacturing yield, and/or reliability.

In part to reduce the opportunity for handling damage, a transport or“shipping” comb is typically installed in an HSA sometime before the HSAis assembled into the disk drive. For example, often HSAs are firstassembled in a different manufacturing facility than where the HDAs thatincorporate such HSAs are later assembled. After the transport comb isinstalled in an HSA, the transport comb typically serves to protect theHSA from handling damage during transport (e.g., by preventing the headsfrom contacting each other). The transport comb also typically serves toseparate the heads from each other enough to facilitate merging of theHSA into the disk drive during disk drive assembly (e.g., to allow thedisks or ramp surfaces to merge between the heads during disk driveassembly), but not to separate the heads from each other so much thatthe bend areas of the suspension assemblies are thereby plasticallydeformed. The transport comb is then typically removed from the HSAduring HDA assembly after the merging step described above.

Unfortunately, the HSA is not as well protected from handling damagebefore or during installation of the transport comb into the HSA. Forexample, the person installing a conventional transport comb into an HSAmust ensure that the separator fingers of the transport comb do notrotate into contact with the suspension assemblies until the transportcomb is at the correct axial position to properly separate the heads. Ifthe person rotates the transport comb (to engage the separator fingerswith the suspension assemblies) at the wrong axial position, then aseparator finger may strike the side of a suspension assembly and/ordeflect a suspension assembly beyond its elastic limit. Thus, there is aneed in the art for a transport comb that reduces the risk of damage toan HSA during installation of the transport comb (into the HSA).

SUMMARY

A head stack assembly (HSA) for a disk drive is disclosed and claimed.The HSA includes an actuator having an actuator body and an actuator armextending from the actuator body. The actuator arm includes a toolinghole and a mass-reduction opening, and defines an actuator arm thicknessadjacent the mass-reduction opening. The HSA includes a head gimbalassembly (HGA) attached to the actuator arm. The HGA includes a readhead and a suspension assembly supporting the read head. The HSAincludes a transport comb during a phase of manufacture of the diskdrive. The transport comb includes a comb body and an alignment pinextending from the comb body into the tooling hole of the actuator arm.At least one separator finger extends from the comb body. The separatorfinger is not in contact with the suspension assembly of the HGA withthe transport comb in a first angular orientation with respect to theactuator arm. The separator finger is in contact with the suspensionassembly of the HGA with the transport comb in a second angularorientation with respect to the actuator arm. The transport combincludes a restraining tower extending from the comb body into themass-reduction opening of the actuator arm. The restraining towerincludes a first lobe that fits within the mass-reduction opening withthe transport comb in the first angular orientation. The first lobe doesnot fit within the mass-reduction opening with the transport comb in thesecond angular orientation. The restraining tower also includes a firstneck that fits within the mass-reduction opening with the transport combin the first and second angular orientations. The first neck has a neckheight that is greater than the actuator arm thickness.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a head stack assembly (HSA)with transport comb according to an embodiment of the present invention.

FIG. 2 is an assembled perspective view of the HSA of FIG. 1.

FIG. 3 is a perspective view of the transport comb of FIG. 1.

FIG. 4 is a side view of an HSA, with transport comb partially inserted,according to an embodiment of the present invention.

FIG. 5 is a side view of an HSA, with transport comb fully inserted,according to an embodiment of the present invention.

FIG. 6A depicts an HSA according to an embodiment of the presentinvention, having a transport comb in a first angular orientation.

FIG. 6B depicts the HSA of FIG. 6A, with the transport comb in a secondangular orientation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 depicts an exploded perspective view of a head stack assembly(HSA) 100. FIG. 2 depicts a non-exploded perspective view of the sameHSA 100. The HSA 100 includes an actuator 110 that has an actuator body112 and a plurality of actuator arms 114, 116, 118 extending from theactuator body 112. In certain embodiments, the actuator body may befabricated of a metal material such as aluminum, stainless steel,magnesium, beryllium, or an alloy thereof, by casting, machining, and/orforging. The actuator 110 of FIG. 1 also includes a coil 106 and anactuator pivot bearing 108. Each of the plurality of actuator arms 114,116, 118 includes a tooling hole 120 and a mass-reduction opening 124.In the embodiment of FIG. 1, the mass-reduction opening 124 is ovalshaped, however the present invention contemplates that other shapes maybe used for the mass-reduction opening (e.g., round, rectangular,oblong, irregular, triangular, or a combination of such shapes). Each ofthe plurality of actuator arms 114, 116, 118 is spaced apart fromanother by an actuator arm spacing 128, and defining an actuator armthickness 132 adjacent the mass-reduction opening 124.

The actuator 110 as shown in FIG. 1 is intended for use in a disk drive(not shown) that would include two disks: an upper disk and a lowerdisk. Accordingly, in the embodiment of FIG. 1, head gimbal assembly(HGA) 136 is attached to actuator arm 118, HGAs 138 and 140 are attachedto actuator arm 116, and HGA 142 is attached to actuator arm 114. In theembodiment of FIG. 1, each of the HGAs 136, 138, 140, and 142 includes aread head (e.g., read head 144 of HGA 138) and a suspension assemblysupporting the read head (e.g., the rest of HGA 138 other than read head144). However, it is contemplated that the present invention may be usedwith an actuator that is designed for use in a so-called depopulateddisk drive, in which case one or more of the HGAs shown in FIG. 1 may beabsent. For example, if the actuator 110 of the embodiment of FIG. 1were to be used in a depopulated disk drive in which the lower disk werenot present, then HGAs 140 and 142 may be absent (e.g., replaced withdummy masses that would attribute similar dynamic characteristics to theactuator arms 114 and 116). On the other hand, if the actuator 110 ofthe embodiment of FIG. 1 were to be used in a depopulated disk drive inwhich the upper disk were not present, then HGAs 136 and 138 may beabsent (e.g., replaced with dummy masses that would attribute similardynamic characteristics to the actuator arms).

The HSA 100 of the embodiment of FIG. 1 also includes a transport comb150. The transport comb 150 includes a comb body 152 and an alignmentpin 154 extending from the comb body 152 into the tooling hole 120. Thecomb body 152 may comprise a plastic material, for example a plasticmaterial that is doped with a lubricant. One example of such a materialwould be a polycarbonate material doped with polytetrafluoroethylene(PTFE). Another example would be a polyetherimide material doped withpolytetrafluoroethylene (PTFE). The comb body 152 may comprise a plasticmaterial doped with a more electrically conductive material (e.g., aliquid crystal polymer material doped with carbon).

In the embodiment of FIG. 1 the alignment pin 154 preferably has a roundcross-section and the tooling hole 120 is preferably round. However,other arrangements that preserve alignment might be used, such as asquare or octagonal cross-section in a round hole or a roundcross-section in a square or hexagonal hole. The transport comb 150 alsoincludes separator fingers 156 and 158 that extend from the comb body152. In the embodiment of FIG. 1, the separator fingers 156 and 158include conical end regions 157 and 159, respectively, to enhanceseparation performance. However, in certain other embodiments, theconical end regions 157 and 159 may be replaced with a region that istapered in other than conical fashion (e.g., flattened wedge) and/or aregion that includes a blunted end portion.

In the embodiment of FIG. 1, the transport comb 150 may be rotated sothat the separator fingers 156, 158 are not in contact with anysuspension assembly of the plurality of HGAs 136, 138, 140, and 142.After such a rotation, the angular orientation of the transport comb 150may be referred to as a “first angular orientation.” However, thetransport comb 150 may also be rotated so that the separator finger 156is brought between and in contact with the suspension assemblies of HGAs136 and 138, and the separator finger 158 is brought between and incontact with the suspension assemblies of HGAs 140 and 142. After such arotation, the angular orientation of the transport comb 150 may bereferred to as a “second angular orientation.” In the embodiment of FIG.1, rotation of the transport comb 150 from the first angular orientationto the second angular orientation may be facilitated by a finger grip153 that extends from the comb body 152.

In the embodiment of FIG. 1, whether the transport comb 150 can berotated into the second angular orientation is determined by thegeometry of a restraining tower 160 that extends from the comb body 152into the mass-reduction opening 124. Specifically, whether the transportcomb 150 can be rotated into the second angular orientation isdetermined by the presence or absence of mechanical interference betweenthe restraining tower 160 and an interior contour of the mass-reductionopening 124. Likewise, whether the transport comb 150 can be installedinto the HSA 100 is also determined by the presence or absence ofmechanical interference between the restraining tower 160 and aninterior contour of the mass-reduction opening 124, so that suchinstallation is permitted only when the separator fingers 156, 158 areangularly displaced away from the HGAs 136, 138, 140, and 142.

FIG. 3 is a perspective view of the transport comb 150 of the embodimentof FIGS. 1-2. The restraining tower 160 of the transport comb 150 has afirst lobe 162 that fits within the mass-reduction opening 124 with thetransport comb 150 in the first angular orientation. The first lobe 162does not fit within the mass-reduction opening 124 with the transportcomb 150 in the second angular orientation. The first lobe 162 has alobe height 166 that is less than the actuator arm spacing 128. Therestraining tower 160 includes a first neck 164 that fits within themass-reduction opening 124 with the transport comb 150 in the first andsecond angular orientations. The first neck 164 has a neck height 168that is greater than the actuator arm thickness 132. As shown in FIG. 3,the first neck 164 is not aligned with the center of the first lobe 162,but rather is aligned with a side of the first lobe 162. In this regard,the first lobe 162 of the embodiment of FIG. 1 need not be concentricabout other portions of the restraining tower 160 such as the first neck164.

In the embodiment of FIG. 3, the restraining tower 160 of the transportcomb 150 also has a second lobe 172 that fits within the mass-reductionopening 124 with the transport comb 150 in the first angularorientation. The second lobe 172 does not fit within the mass-reductionopening 124 with the transport comb 150 in the second angularorientation. The second lobe 172 has a lobe height 176 that is less thanthe actuator arm spacing 128. The restraining tower 160 includes asecond neck 174 that fits within the mass-reduction opening 124 with thetransport comb 150 in the first and second angular orientations. In theembodiment of FIG. 3, the second neck 174 has a neck height 178 that isgreater than the actuator arm thickness 132.

In the embodiment of FIG. 1, the transport comb 150 also includes amotion limiting projection 180 that, with the transport comb rotatedinto the second angular orientation, fits between (but under normalconditions does not contact) the suspension assemblies of HGAs 136 and138. Under conditions of mechanical shock, the motion limitingprojection 180 may help reduce the likelihood of contact between theheads of HGAs 135 and 138. Also in the embodiment of FIG. 1, thetransport comb 150 includes a motion limiting projection 182 that, withthe transport comb rotated into the second angular orientation, fitsbetween (but under normal conditions does not contact) the suspensionassemblies of HGAs 140 and 142. Under conditions of mechanical shock,the motion limiting projection 182 may help reduce the likelihood ofcontact between the heads of HGAs 140 and 142.

FIG. 4 depicts the HSA 100 with the transport comb 150 positioned suchthat the alignment pin 154 is partially inserted into the tooling hole120 of actuator 110 and such that the restraining tower 160 is partiallyinserted into the mass-reduction opening 124 of actuator 110. Moreparticularly, FIG. 4 depicts a specific amount of insertion whichconstitutes the first opportunity during insertion for the transportcomb 150 to be rotated from the first angular orientation into thesecond angular orientation. Although it is possible to rotate thetransport comb 150 into the second angular orientation with the partialinsertion depicted in FIG. 4, this is not an intended use of thetransport comb 150 because it would serve only to separate HGAs 136 and138 from each other and would not serve to separate HGAs 140 and 142from each other.

In the embodiment shown in FIG. 4, the spacing 128 between actuator arms114 and 116 is preferably the same as that between actuator arms 116 and118. In such an embodiment the lobe heights 166 and 176 shown in FIG. 3are preferably but not necessarily equal. However, in an alternativeembodiment the actuator arm spacings and the lobe heights are not equal.

Also in the embodiment shown in FIG. 4, the thickness 132 of actuatorarm 114 is the same as that of actuator arm 116 or 118. In such anembodiment the neck height 168 shown in FIG. 3 is preferably but notnecessarily equal to the neck height 178. However, in certainembodiments the thickness of the actuator arms may be unequal. Forexample, actuator arm 116 may be made thicker and stiffer than actuatorarm 114 (or 118) to match one or more dynamic response frequencies inlight of the fact that actuator arm 116 is a middle actuator arm thatcarries the mass of two HGAs (i.e. HGAs 138 and 140) rather than onlyone HGA. In an embodiment where actuator arm 116 is thicker thanactuator arms 114 or 118, the neck height 178 will preferably but notnecessarily exceed the neck height 168.

FIG. 5 depicts the HSA 100 with the transport comb 150 positioned suchthat the alignment pin 154 is fully inserted into the tooling hole 120of actuator 110 and such that the restraining tower 160 is fullyinserted into the mass-reduction opening 124 of actuator 110. Moreparticularly, FIG. 5 depicts a specific amount of insertion whichconstitutes the second opportunity during insertion for the transportcomb 150 to be rotated from the first angular orientation into thesecond angular orientation. The full insertion depicted in FIG. 5represents an intended use of the transport comb 150 because it wouldserve to separate HGAs 136 and 138 from each other and it would serve toseparate HGAs 140 and 142 from each other.

Because the restraining tower 160 of the transport comb 150 will notallow the transport comb 150 to be rotated from the first angularorientation into the second angular orientation except at the specificinsertions depicted in FIG. 4 and in FIG. 5, the risk of handling damageto the HSA 100 may be reduced. Specifically, the risk of handling damagedue to an impact by separator fingers 156, 158 into the side of one ormore of HGAs 136, 138, 140, and/or 142, during the rotation of transportcomb 150 into the second angular orientation, is reduced because suchrotation is prevented by the restraining tower 160 except at a discretenumber of safe insertion positions (i.e. in this embodiment, theinsertion positions depicted in FIG. 4 and FIG. 5, respectively).

FIGS. 6A and 6B depict an HSA 600 with a transport comb 650 according toan embodiment of the present invention. The transport comb 650 includesa comb body 652, at least one separator finger 656 that extends from thecomb body 652, and a restraining tower that includes at least one lobe662. In the embodiment of FIGS. 6A and 6B, the transport comb 650 alsooptionally includes a motion limiting projection 680.

The HSA 600 of FIGS. 6A and 6B includes at least one actuator arm 618having a mass-reduction opening 624. In the embodiment of FIGS. 6A and6B, the mass-reduction opening 624 is oval shaped, however the presentinvention contemplates that other shapes may be used for themass-reduction opening (e.g., round, rectangular, oblong, irregular,triangular, or a combination of such shapes). At least one HGA 636 isattached to actuator arm 618.

In FIG. 6A, the transport comb 650 is depicted in a first angularorientation so that the separator finger 656 is not in contact with thesuspension assembly of HGA 636, and so that the lobe 662 can fit withinthe mass-reduction opening 624. However, in FIG. 6B the transport comb650 is shown in a second angular orientation where the separator finger656 is in contact with the suspension assembly of HGA 636, but where thelobe 662 cannot fit within the mass-reduction opening 624 (e.g., thelobe 662 may be locked underneath the mass-reduction opening 624 so thatthe vertical position of the comb 650 relative to the actuator arm 618is constrained). As can be seen by comparison of FIG. 6A with FIG. 6B,the first and second angular orientations are different by an angulardifference about the alignment pin 654 that exceeds a rotation requiredto separate contact between the separator finger 656 and the suspensionassembly of the HGA 636.

Under normal conditions, even with the transport comb 650 in the secondangular orientation, the motion limiting projection 680 preferably doesnot contact flexure 645. However, with the transport comb 650 in thesecond angular orientation, and under conditions of mechanical shock,the motion limiting projection 680 may desirably interfere withexcessive vertical travel of a flexure 645 of the suspension assembly ofHGA 636. Such desirable interference may help reduce the likelihood ofexcessive deflection of the flexure 645 and, in so doing, reduce thelikelihood of undesired and/or uncontrolled plastic deformation of theflexure 645.

In the embodiment of FIGS. 6A and 6B, whether the transport comb 650 canbe rotated into the second angular orientation is preferably determinedby the geometry of the restraining tower that includes the lobe 662 andextends from the comb body 652 into and/or through the mass-reductionopening 624. Specifically, whether the transport comb 650 can be rotatedinto the second angular orientation may be determined by the presence orabsence of mechanical interference between the lobe 662 and an interiorcontour of the mass-reduction opening 624. Likewise, whether thetransport comb 650 can be installed into the HSA 600 is also determinedby the presence or absence of mechanical interference between therestraining tower with lobe 662 and an interior contour of themass-reduction opening 624, so that such installation is permitted onlywhen the separator finger 656 is angularly displaced away from the HGA636. In the embodiment of FIGS. 6A and 6B, rotation of the transportcomb 650 may be facilitated by a finger grip 653 that extends from thecomb body 652.

In the foregoing specification, the invention is described withreference to specific exemplary embodiments thereof, but those skilledin the art will recognize that the invention is not limited thereto. Itis contemplated that various features and aspects of the above-describedinvention may be used individually or jointly and possibly in anenvironment or application beyond those described herein. Thespecification and drawings are, accordingly, to be regarded asillustrative and exemplary rather than restrictive. The terms“comprising,” “including,” and “having,” as used herein are intended tobe read as open-ended terms.

1. A head stack assembly (HSA) comprising: an actuator including anactuator body and an actuator arm extending from the actuator body, theactuator arm including a tooling hole and a mass-reduction opening anddefining an actuator arm thickness adjacent the mass-reduction opening;a head gimbal assembly (HGA), attached to the actuator arm, the HGAincluding a read head and a suspension assembly supporting the readhead; a transport comb comprising: a comb body; an alignment pinextending from the comb body into the tooling hole of the actuator arm;at least one separator finger extending from the comb body, theseparator finger in contact with the suspension assembly of the HGA withthe transport comb in a second angular orientation with respect to theactuator arm, the separator finger not in contact with the suspensionassembly of the HGA with the transport comb in a first angularorientation with respect to the actuator arm; a restraining towerextending from the comb body into the mass-reduction opening of theactuator arm, the restraining tower including a first lobe that fitswithin the mass-reduction opening with the transport comb in the firstangular orientation, the first lobe not fitting within themass-reduction opening with the transport comb in the second angularorientation; and a first neck that fits within the mass-reductionopening with the transport comb in the first and second angularorientations, the first neck having a neck height that is greater thanthe actuator arm thickness.
 2. The HSA of claim 1 wherein the toolinghole is round and the alignment pin is round.
 3. The HSA of claim 1wherein the first and second angular orientations are different by anangular difference about the alignment pin that exceeds a rotationrequired to separate said contact between the at least one separatorfinger and the suspension assembly of the HGA.
 4. The HSA of claim 1wherein the first lobe is not concentric about the first neck.
 5. TheHSA of claim 1 wherein the mass-reduction opening is oblong.
 6. A headstack assembly (HSA) comprising: an actuator including an actuator bodyand a plurality of actuator arms extending from the actuator body, eachof the plurality of actuator arms including a tooling hole and amass-reduction opening, each of the plurality of actuator arms beingspaced apart from another by an actuator arm spacing, and defining anactuator arm thickness adjacent the mass-reduction opening; a pluralityof head gimbal assemblies (HGAs), each of the plurality of HGAs attachedto one of the plurality of actuator arms, each of the plurality of HGAsincluding a read head and a suspension assembly supporting the readhead; a transport comb comprising: a comb body; an alignment pinextending from the comb body into the tooling hole of at least one ofthe plurality of actuator arms; at least one separator finger extendingfrom the comb body, the separator finger in contact with two suspensionassemblies of the plurality of HGAs with the transport comb in a secondangular orientation with respect to the plurality of actuator arms, theseparator finger not in contact with any suspension assembly of theplurality of HGAs with the transport comb in a first angular orientationwith respect to the plurality of actuator arms; a restraining towerextending from the comb body into the mass-reduction opening of the atleast one of the plurality of actuator arms, the restraining towerincluding a first lobe that fits within the mass-reduction opening withthe transport comb in the first angular orientation, the first lobe notfitting within the mass-reduction opening with the transport comb in thesecond angular orientation, the first lobe having a lobe height that isless than the actuator arm spacing; and a first neck that fits withinthe mass-reduction opening with the transport comb in the first andsecond angular orientations, the first neck having a neck height that isgreater than the actuator arm thickness.
 7. The HSA of claim 6 whereinthe tooling hole is round and the alignment pin is round.
 8. The HSA ofclaim 6 wherein the first and second angular orientations are differentby an angular difference about the alignment pin that exceeds a rotationrequired to separate said contact between the at least one separatorfinger and said two suspension assemblies of the plurality of HGAs. 9.The HSA of claim 6 wherein the first lobe is not concentric about thefirst neck.
 10. The HSA of claim 6 wherein the mass-reduction opening isoblong.
 11. The HSA of claim 6 wherein the restraining tower furthercomprises a second lobe that is offset from the first lobe by theactuator arm spacing.
 12. The HSA of claim 6 wherein the comb bodycomprises a plastic material that is doped with lubricant.
 13. The HSAof claim 12 wherein the comb body comprises a polycarbonate materialdoped with polytetrafluoroethylene (PTFE).
 14. The HSA of claim 12wherein the comb body comprises a polyetherimide material doped withpolytetrafluoroethylene (PTFE).
 15. The HSA of claim 6 wherein the combbody comprises a plastic material doped with a more electricallyconductive material.
 16. The HSA of claim 15 wherein the comb bodycomprises a liquid crystal polymer material doped with carbon.